The present invention relates generally to water purification, and specifically to water pasteurization and turbine power generation.
Traditional methods for purifying wastewater include chlorination, exposure to ultraviolet (UV) radiation, and ultra filtration. Unfortunately, there are drawbacks to each of these methods.
Chlorination involves the treatment of water with chlorine or a chlorine compound. If the chlorine concentration is great enough, the treated water tends to smell and taste bad. Some people object to the smell and taste of very small amounts of chlorine. In addition, chlorination can be harmful to people's health. If water supplies contain humic compounds, which form as a part of the decomposition of organic materials such as leaves, grass, wood, or animal wastes, chlorination of such water can produce trihalomethanes (THMs). Because THMs are very seldom associated with groundwater, they are primarily a concern when surface water supplies are used. Lifetime consumption of water supplies with THMs at a lever greater than 0.10 milligrams per liter is considered by the Environmental Protection Agency to be a potential cause of cancer.
Treatment of water by exposure to ultraviolet radiation is complicated and maintenance intensive. It involves the use of UV lamps, which must be replaced periodically. UV treatment also often utilizes reflectors for focusing the UV light toward the water. Such reflectors must be cleaned from time to time. Also, it is generally desirable for the water flow through the UV treatment chambers to be laminar, to promote uniformity of UV exposure. This requires the use of baffles and specially designed treatment chambers, which increases costs.
Filtration involves causing the water to flow through a series of filters. Like UV treatment, filtration is maintenance intensive. The filters must be cleaned and/or replaced periodically. Further, filtration is often a slow process.
Pasteurization is yet another known method for purifying water. It involves heating water to a temperature of at least 150-170° F. Pasteurization is typically conducted at low water volumes, such as in campsites and other remote, rural locations. Small, portable solar water pasteurization units, or solar cookers, are sometimes used for pasteurizing water from solar heat. Generally, pasteurization is not used for large-scale water treatment due to the high costs associated with heating large amounts of water.